Confused about T14 Feat of Strength achievment

Hello guys. So a bit earlier this week , blizzard posted this: "When Patch 5.2 goes live, all players who have defeated Will of the Emperor, Grand Empress Shek’zeer, and/or Sha of Fear prior to the release of Patch 5.2 will receive a Feat of Strength to mark their accomplishments. ".

Now , i'll admit , English is not my first language but I find myself being pretty good with it. But , for the life of me , I cannot understand what exactly do they mean in this part:" Will of the Emperor, Grand Empress Shek’zeer, and/or Sha of Fear". Does the 'and/or' means that in order to be eligible to receive the FoS , one could only kill the Sha of Fear , without clearing the rest? Or am I not getting it right?

It's pretty embarrassing because I guess the answer is obvious , but I just cannot figure this out :[

Yes it appears there are individual FoS for each on normal or heroic difficulty. So If you kill will and empress on normal you'll get an 'ahead of the curve' FoS for those 2. Whereas if you clear everything on normal and heroic, you'll get 3 x 'ahead of the curve' FoS's and 3 x 'cutting edge' FoS's.

I know they originally planned for them to achieved by killing said boss before being nerfed, but changed to when 5.2 is released. Which I guess since 5.0 raids are getting a nerf then is the same thing but whether they were individual or a single FoS for all I am not sure.

You get a FoS as soon as 5.2 hits for:
- Will of the Emperor Normal Kill (Ahead of the Curve: Will of the Emperor)
- Shek'zeer Normal Kill (Ahead of the Curve: Grand Empress Shek'zeer)
- Sha of Fear Normal Kill (Ahead of the Curve: Sha of Fear)

You get a FoS as soon as you kill the boss, before 5.2, for:
- Will of the Emperor HC Kill (Cutting Edge: Will of the Emperor)
- Shek'zeer HC Kill (Cutting Edge: Grand Empress Shek'zeer)
- Sha of Fear HC Kill (Cutting Edge: Will of the Emperor)

lets say you ve done "Will of emperor" on heroic version but you dont have it on normal,
when 5.2 will hit, will you have both "Cutting Edge": Heroic Emperor AND AHEAD OF CURVE : Normal Emperor
or no matter if you ve done in heroic, you also need to do it on normal version to get ahead of Curve FoS ?